Halogen–lithium exchange between substituted dihalobenzenes and butyllithium: application to the regioselective synthesis of functionalized bromobenzaldehydes
作者:Marek Dąbrowski、Joanna Kubicka、Sergiusz Luliński、Janusz Serwatowski
DOI:10.1016/j.tet.2005.04.051
日期:2005.7
Halogen–lithium interconversion reactions between unsymmetrically substituted mono- and bifunctional dihalobenzenes C6H3XHal2 and C6H2XYHal2 (Hal=Br, I; X, Y=F, OR, CF3, CH(OMe)2) and butyllithium were investigated. The resultant organolithium intermediates were converted into the corresponding benzaldehydes in moderate to good yields. As a rule, bromine atoms in the position ortho to the functional group
非对称取代的单官能和双官能二卤代苯C 6 H 3 XHal 2和C 6 H 2 XYHal 2之间的卤素-锂互变反应(Hal = Br,I; X,Y = F,OR,CF 3,CH(OMe)2)研究了丁基锂和丁基锂。将所得的有机锂中间体以中等至良好的产率转化成相应的苯甲醛。通常,邻位的溴原子官能团中的α优先被锂取代。具有双功能系统的分子内竞争实验表明,与甲氧基和二甲氧基甲基相比,氟能够更强地激活相邻的溴原子。用碘代替未活化的溴后,由于优选的碘-锂交换,可以完全逆转这种反应模式。